Contraception with a foreign body in the uterine cavityof a woman -- the intrauterine contraceptive device, commonly known as an IUD -- has been practiced by the medical profession with an increasing measure of success. Thus the pregnancy rate with an IUD in position can be at least as low as 1.4%.
One proposed IUD is in the form of a zig-zag, others are T-shaped, bow-shaped, coiled and closed perimeters such as O-shapes.